Electric heating assemblies



March 2, 1965 ELECTRIC HEATING R. L. POST ASSEMBLIES Filed Feb. 1, 1962 M ii in INVENTOR. RKZHARD L PosT Y M Kznfi United States Patent Wee 3,171,948 ELECTRIC HEATING ASSEMBLIES Richard L. Post, Glenshaw, Pa., assignor to Edwin L. Wiegand Company, Pittsburgh, Pa. Filed Feb. 1, 1962, Ser. No. 170,333 Claims. (Cl. 219-463) My invention relates to electric heating assemblies, more particularly to an assembly of a heater sheath with a support, and the principal object of my invention is to provide new and improved assemblies of this character.

In the drawing accompanying this specification and forming a part of this application, there is shown, for purpose of illustration, an embodiment which my inven tion may assume, and in this drawing:

FIGURE 1 is a fragmentary perspective view of an assembly illustrating a presently preferred embodiment of my invention,

FIGURE 2 is an enlarged cross-section of the construction shown in FIGURE 1, and

FIGURES 3 through 5 illustrate the invention applied to heater sheaths of various cross-sections.

The invention herein disclosed is particularly useful in securely holding a metallic heater sheath and an underlying support of metal strip in assembled relation. Application of this assembly may be wide spread in the electric heating field. For example, the application may be made in a range unit assembly, such as that disclosed in Patent 2,413,478, issued December 31, 1946, to Edwin L. Wiegand. In such patent, an elongated heating element is formed to provide a flat convoluted active heating portion which is supported by and connected to a spider formed of a plurality of sheet-metal legs. A vessel to be heated is adapted to rest upon the flat upper surface of the active heating portion and therefore it is imperative that no connection extends above such upper surface to disturb heating engagement with the vessel.

In the aforementioned Wiegand patent, L-shaped rods are welded to the underside of the heating element, the rods fitting within apertures formed in the spider legs. This formed a very satisfactory connection and the present invention is designed to produce a somewhat similar connection of reduced cost.

FIGURES l and 2 disclose a metal heater sheath of generally triangular across-section, but it is to be understood that the invention may be used with equal facility when the sheath is rectangular in cross-section, as shown in FIGURE 3, or is round in cross-section as shown in FIGURE 4, or modified round as shown in FIGURE 5.

In the usual manufacture of an electric heater, the sheath is initially rectilinear and round in cross-section. A heating resistor 11 and electric-insulating heat-conducting material 12 are disposed within the sheath, the latter material usually being granular refractory, such as magnesium oxide. The heater thus formed is subjected to a reduction in transverse size, either by a rolling action or by side pressing, to highly compact the refractory material, and the cross-sectional shape of the heater may be changed at this time or at a latter stage of manufacture.

In any event, during a suitable stage of manufacture, localized bulges 14-14 are produced in the sheath for a purpose to later appear. The heater normally underlies and supports an object or vessel to be heated and therefore it has an upper surface 15 which is engageable with such object or vessel. In accordance with good heat transfer principles, the aforementioned interengagement should be free of any interruptions and therefore it is essential that the upper surface 15 be free to directly engage the object or vessel to be heated.

Accordingly, the bulges 1414 are necessarily formed below the upper surface 15 as shown in the drawing. In

3,171,948 Patented Mar. 2, 1965 FIGURES 1 and 2, the heater has been formed to gen erally triangular cross-section, the upper surface 15 forming the top leg of the triangle being generally flat and the two side surfaces 16-16 inclining toward each other and being joined by a lower rounded portion 26. The side surfaces may be fiat or may bulge slightly inwardly, as shown in the drawing.

At a localized place (or places) along the heater, the bulges 1414 are formed in the sides 16-16. The heater support 17 is preferably formed of sheet metal and is positioned transversely of the heater and edgewise against the lower rounded portion 16 of the heater. A pair of claws 18-18 extend upwardly from the upper edge 19 of the support 17, the claws defining between them a recess 20 which receives the transversely extending heater. To assemble the heater with the support, it is merely necessary to apply a pressing force against the claws to deform the upper ends 2121 thereof inwardly toward each other and over the upper portion of a respective bulge 14 to securely lock the heater to the support and against the bottom of the recess 20.

FIGURES 3 through 5 disclose the invention applied to heaters of various cross-sections and corresponding parts are designated by the same reference numerals.

In view of the foregoing, it will be apparent to those skilled in the art that I have accomplished at least the principal object of my invention and it will also be apparent to those skilled in the art that the embodiment herein described may be variously changed and modified without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence it will be appreciated that the herein disclosed embodiment is illustrative only, and that the invention is not limited thereto.

I claim:

1. An electric heater assembly, comprising an electric heating element including an elongated metal sheath enclosing an electric resistor and heat-conducting electricinsulating material, said sheath in cross-section having an upper surface of constant Width and disposed in a horizontal plane throughout its active heating length whereby an object to be heated may have its flat under surface disposed upon said upper surface in substantially uniform heat transfer contact therewith, said sheath having opposed side surfaces which extend downwardly from respective sides of said upper surface, a metallic support member extending cross-wise of and under said heating element, said sheath having transversely opposed bulges in respective side surfaces which are localized at the place on said side surfaces where said metal support member crosses said metal sheath, said metal support member having a recess into which the adjoining lower portion of said metal sheath is received, said recess being of a width to closely receive said bulges between its defining side margins, portions of said support member at the upper part of said side margins being deformed toward each other and over the upper portions of respective bulges to hold said heating element assembled with said metal support member, said bulges being disposed sufficiently below said upper surfaces so that the deformed portions of said support member are located below the plane of said upper surface whereby to be free of interference with heat transfer contact between said upper surface and the undersurface of the object to be heated.

2. The construction according to claim 1 wherein said bulges are curved in vertical cross-section and opposed side margins defining said recess and adjoining the lower portions of said bulges are correspondingly curved to contact the latter.

3. The construction according to claim 1 wherein said sheath is generally triangular in cross-section.

4. The construction according to claim 1 wherein said sheath is round in cross-section.

5. The construction according to claim 1 wherein said sheath is rectangular in cross-section.

References Cited by the Examiner UNITED STATES PATENTS 7/ 36 Schurmann 29513 5/ 39 Meirath 29 -513 Vogel v 219463 Tuttle 219-463 Platt 29509 Young 219-463 Vallorani et a1. 219-455 Fisher 219-553 RICHARD M. WOOD, Primary Examiner. 

1. AN ELECTRIC HEATER ASSEMBLY, COMPRISING AN ELECTRIC HEATING ELEMENT INCLUDING AN ELONGATED METAL SHEATH ENCLOSING AN ELECTRIC RESISTOR AND HEAT-CONDUCTING ELECTRICINSULATING MATERIAL, SAID SHEATH IN CROSS-SECTION HAVING AN UPPER SURFACE OF CONSTANT WIDTH AND DISPOSED IN A HORIZONTAL PLANE THROUGHOUT ITS ACTIVE HEATING LENGTH WHEREBY AN OBJECT TO BE HEATED MAY HAVE ITS FLAT UNDER SURFACE DISPOSED UPON SAID UPPER SURFACE IN SUBSTANTIALLY UNIFORM HEAT TRANSFER CONTACT THEREWITH, SAID SHEATH HAVING OPPOSED SIDE SURFACES WHICH EXTEND DOWNWARDLY FROM RESPECTIVE SIDES OF SAID UPPER SURFACE, A METALLIC SUPPORT MEMBER EXTENDING CROSS-WISE OF AND UNDER SAID HEATING ELEMENT, SAID SHEATH HAVING TRANSVERSELY OPPOSED BULGES IN RESPECTIVE SIDE SURFACES WHICH AR LOCALIZED AT THE PLACE ON SAID SIDE SURFACES WHERE SAID METAL SUPPORT MEMBER CROSSES SAID METAL SHEATH, SAID METAL SUPPORT MEMBER HAVING A RECESS INTO WHICH THE ADJOINING LOWER PORTION OF SAID METAL SHEATH IS RECEIVED, SAID RECESS BEING OF A WIDTH TO CLOSELY RECEIVE SAID BULGES BETWEEN ITS DEFINING SIDE MARGINS, PORTIONS OF SAID SUPPORT MEMBER AT THE UPPER PART OF SAID SIDE MARGINS BEING DEFORMED TOWARD EACH OTHER AND OVER THE UPPER PORTIONS OF RESPECTIVE BULGES TO HOLD SAID HEATING ELEMENT ASSEMBLED WITH SAID METAL SUPPORT MEMBER, SAID BULGES BEING DISPOSED SUFFICIENTLY BELOW SAID UPPER SURFACES SO THAT THE DEFORMED PORTIONS OF SAID SUPPORT MEMBER ARE LOCATED BELOW THE PLANE OF SAID UPPER SURFACE WHEREBY TO BE FREE OF INTERFERENCE WITH HEAT TRANSFER CONTACT BETWEEN SAID UPPER SURFACE AND THE UNDERSURFACE OF THE OBJECT TO BE HEATED. 